Surface maintenance vehicles that perform a single surface maintenance or surface conditioning task are, of course, well known. Surface maintenance vehicles are generally directed to perform work in diverse maintenance, conditioning and cleaning applications such as for flooring surfaces. In this disclosure, the term floor refers to any support surface, such as, among others, floors, pavements, road surfaces, ship decks, and other surfaces to be cleaned and the like.
Commonly floor or surface maintenance machines are constructed having a single surface conditioning appliance or system so as to only sweep, others to scrub, while still others only to polish or burnish. It is of course possible to construct a single surface maintenance machine to perform one or more of the aforementioned surface maintenance tasks. One example of a multi-task floor conditioning machine is disclosed in U.S. Pat. No. 3,204,280, entitled “Floor Cleaning & Waxing Machine,” the entire disclosure of which is incorporated by reference herein in its entirety for any and all purposes. Another is disclosed in U.S. Pat. No. 5,483,718, entitled, “Floor Scrubbing Machine Having Impact Energy Absorbtion,” the entire disclosure of which is incorporated be reference herein in its entirety for any and all purposes. Disclosed therein is a forward mounted scrubber assembly that is followed by a squeegee assembly.
Scrubbing systems are well known in the art. Scrubbing systems commonly include a driver assembly and a rotatable scrubber in the form of a brush, pad, or the like. A control device may be utilized for controlling the degree of scrubbing (typically a function of down force applied through the scrubber) applied to a floor surface depending upon the type and/or condition of floor surface intended to be scrubbed. The scrubber driver assemblies for scrubbing systems are well known in the art and commonly include one or more rotatable brushes driven by a driver motor affixed to a scrubber head. Scrubber heads of the prior art have been selectively raised and lowered by an actuator coupled to the driver so as to achieve an intended down force or scrubbing pressure of the scrub pad against a floor surface. Examples of the latter are taught in U.S. Pat. Nos. 4,757,566, 4,769,271, 5,481,776, 5,615,437, 5,943,724, and 6,163,915, the entire disclosures of which are incorporated by reference herein in its entirety for any and all purposes.
Limit switches have been used to determine the relative position of the actuator tool. Limit switches are mechanical switches and, depending particularly on the operating environment, may be prone to damage or failure. Some limit switches are integrated within the housing of linear actuator to minimize damage or obstruction of the switch contacts. In some applications, a pair of limit switches can be used to determine the end of range positions of the actuator. In such applications, the pair of limit switches are unable to provide information as to actuator tool position within the range of limits.
Accordingly, it would be desirable to provide an apparatus and method for determining the position of an actuator or tool controlled by an actuator. Additionally, it would be desirable to eliminate the use of one or more limit switches to determine actuator or tool position.